It is known that the server of, for example, an “Internet Service Provider” (ISP) can announce to a user who is logging in or has already logged in that there is new e-mail, news, or other items for that user. Another possibility is that the user, after logging in to the server, asks if any new items have arrived. Alternatively, an ISP or other server can activate the local terminal in some other way. For example, the ISP can update software or databases present in the terminal, send out recent news reports, etc.
All this is, however, only possible if there is an actual connection with the server. If a user wishes to be notified as soon as any new mail etc. arrives on the server, this is only possible if there is a continuous or very frequently established connection with the server. If the connection runs via e.g. a PSTN or an ISDN connection, which is not usually continuously open, this means that the user must regularly establish a connection in order to check whether any mail, messages, updates, etc. are present on the server. Since this will often not be the case, however, this procedure is both inefficient and costly both for the users and for the service provider. Of course, keeping a connection open continuously is even more expensive for residential and small business users.